When transmitting AV information in digital form, there is a camera module which is an important device used for the input and output of the information. Camera modules are mounted on mobile phones, laptop computers, digital cameras, digital video cameras and the like. For its photographing functions, a camera module may have a static still photographing function, as well as a dynamic monitoring function (for example, a rear monitor in an automobile etc.).
Until now, the plastic lenses of camera modules mounted on mobile phones have not been able to withstand solder reflow, which has prevented camera modules from being surface mounted as a whole unit. Therefore, the assembly step onto a substrate has either been carried out by surface mounting the module parts other than the lens portion, and then mounting the lens, or by assembling the whole camera module and mounting the camera module on the substrate by some other method.
Recently, inexpensive plastic lenses which are capable of withstanding solder reflow have been developed, giving rise to an environment in which surface mounting of the whole camera module can be carried out. Accordingly, liquid crystal polymers which have a high heat resistance and which can be molded in thinner wall thickness are now being used for the “lens barrel portion” (section where the lens is placed), the “mount holder portion” (section in which the barrel is mounted and which is fixed to the substrate), the “CMOS (image sensor) frame,” and the “shutter and shutter bobbin portion” (refer to Patent Document 1).
For a typical camera module mounted with a fixed focus optical system, a CMOS (image sensor) has a structure in which a multilayer chip is mounted on a signal processing chip. In the assembly step of the CMOS, manual focus adjustment of the optical parts system becomes necessary (adjustment for optimizing the focus distance by threadedly moving the lens barrel portion screwed on a mount holder portion by a screw and by changing the distance between the lens and the image sensor) (Patent Document 1). However, for conventional liquid crystal polymer compositions, in this focus adjustment step, powders (particles) composed of the resin composition exfoliate from the lens barrel, the portions where both the mount holder and lens barrel wear against each other during screwing, and the surfaces of both molded articles during the threaded movement of the lens barrel portion. These powders land on the CMOS (image sensor) or on an (IR cutting) filter, thereby become one of large causes to induce image defects. Powder exfoliation can also occur during use of a product in which these members are built. Therefore, as the material used for the lens barrel portion, mount holder portion, CMOS (image sensor) frame, shutter, shutter bobbin portion and the like of camera modules, there is a need to provide a liquid crystal polyester composition having a low level of powder (particle) exfoliation.
As the material used for the above-described camera module part, although several further examples using a liquid crystal polymer can be cited in addition to Patent Document 1 (Patent Documents 2 and 3), none of these examples touches on a method for controlling the occurrence of powders (particles) during the assembly step as described above, or on the development of a resin composition in which there is little occurrence of powder (particle) exfoliation.
Conventionally, it is known to add talc to improve the anisotropy, warpage, and heat resistance of a liquid crystal polyester resin molded article (for example, refer to Patent Documents 4 to 6). Although there are also documents which discuss the surface appearance of such a molded article (refer to Patent Document 7), the documents are completely silent about a resin composition having such strict surface transferability—reducing as much as possible the occurrence of exfoliations of (from) the surface—of a molded article as in the present usages.
Furthermore, conventionally, to improve the mechanical properties, anisotropy, warpage, and heat resistance of a liquid crystal polyester resin, it is known to add a plate-like substance such as talc and a fibrous substance such as a glass fiber. Although strength and elastic modulus improve by adding a fibrous substance such as a glass fiber, there is the drawback that the effect of an improvement in anisotropy is small. Although anisotropy improves by adding a plate-like substance such as talc, there is the drawback that the effects of an improvement in the strength and elastic modulus are small. Therefore, attempts are being made to improve the balance between strength and elastic modulus, anisotropy and the like by adding the fibrous substance such as a glass fiber and the plate-like substance such as talc in various combinations (for example, refer to Patent Documents 8 to 12).
In addition, although there are documents which discuss using titanium oxide as a white pigment in a liquid crystal polyester resin used for a reflection plate made from resin to improve the reflectivity, dimensional stability against heat, and color phase stability thereof (for example, Patent Documents 13 to 15), the number of patent documents which evaluate and describe in the examples titanium oxide as a filler is surprisingly low (although there are many cases which describe titanium oxide as a common filler for a liquid crystal polyester resin). About the only case which catches the eye is a case (refer to Patent Document 16) which attempts to suppress contamination of the mold during molding and a decrease in glossiness of a surface of a molded article by adding a small amount of surface-treated titanium oxide. However, knowledge concerning a preferred plate-like substance such as talc, fibrous substance such as a glass fiber, and titanium oxide to maintain and improve a good balance between strength and elastic modulus, anisotropy and the like is yet to be attained concerning the production of a resin composition having such strict surface transferability—reducing as much as possible the occurrence of exfoliations of (from) the surface—of the molded article according to the present usages by further adding titanium oxide to a liquid crystal polyester resin which is compounded from a mixture of talc, a glass fiber and the like.    Patent Document 1: Japanese Patent Application Laid-Open No. 2006-246461    Patent Document 2: Japanese Patent Application Laid-Open No. 2008-028838    Patent Document 3: Japanese Patent Application Laid-Open No. 2008-034453    Patent Document 4: Japanese Patent Application Laid-Open No. Hei 04-13758    Patent Document 5: Japanese Patent Application Laid-Open No. 2001-207054    Patent Document 6: Japanese Patent Application Laid-Open No. Hei 06-207083    Patent Document 7: Japanese Patent Application Laid-Open No. 2003-128893    Patent Document 8: Japanese Patent Application Laid-Open No. Hei 04-76049    Patent Document 9: Japanese Patent Application Laid-Open No. Hei 10-219085    Patent Document 10: Japanese Patent Application Laid-Open No. 2000-178443    Patent Document 11: Japanese Patent Application Laid-Open No. 2002-294038    Patent Document 12: Japanese Patent Application Laid-Open No. 2003-246923    Patent Document 13: Japanese Examined Patent Application Publication No. Hei 06-38520    Patent Document 14: Japanese Patent Application Laid-Open No. 2004-256673    Patent Document 15: Japanese Patent Application Laid-Open No. 2007-182505    Patent Document 16: Japanese Patent Application Laid-Open No. Hei 08-302172